Actually, talking serious and stuff, there is a good deal of literature out there analyzing how player performance changes with age. This is perhaps best known for baseball, where most often players continue at their average performance until they suddenly drop off significantly. This is perhaps what bigfishy experienced with his player. Of course it's possible that fishy's player started with low sublevels, and as such, his actual performance might not have declined as fast as all the red arrows accumulated.
Of course, basketball player performance isn't the same thing, though many studies have demonstrated sudden, significant drops in player ability during aging. There's also a random aspect to it as well. Some players maintain their ability longer than others. But I'd hazard a guess that over a wider base of BB player observations, is pretty well modeled in the current aging process.